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<blockquote class="extDef">NOTE&nbsp; Definition according to ISO/CD 10303-42:1992<br>
A vertex is the topological construct corresponding to a point. It has dimensionality 0 and extent 0. The domain of a vertex, if present, is a point in m dimensional real space <em>R<sup>M</sup></em>; this is represented by the vertex point subtype.</blockquote> 

<blockquote class="note">NOTE&nbsp; Entity adapted from <strong>vertex</strong> defined in ISO 10303-42.</blockquote>
<blockquote class="history">HISTORY&nbsp; New entity in IFC2.0</blockquote> 

<p class="spec-head">Informal Propositions:</p>
<ol>
<li>The vertex has dimensionality 0. This is a fundamental property of the vertex.</li>
<li>The extent of a vertex is defined to be zero.</li>
</ol>